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Chemistry of Aqueous Lead(II) Ions

This page discusses the precipitation of insoluble lead(II) compounds from aqueous lead(II) ions in solution. It describes the formation of lead(II) hydroxide, lead(II) chloride, lead(II) iodide and lead(II) sulfate. Because many lead(II) compounds are insoluble, a common source of aqueous lead(II) ions is lead(II) nitrate; this source is assumed in all following examples.

Making lead(II) hydroxide

If a small amount of sodium hydroxide solution is added to colorless lead(II) nitrate solution, a white precipitate of lead(II) hydroxide is produced:

\[ Pb^{2+} + 2OH^- (aq) \rightarrow Pb(OH)_2(s)\]

If more sodium hydroxide solution is added, the precipitate redissolves, forming colorless sodium plumbate(II) solution:

\[ Pb(OH)_2 (s) + 2OH^- (aq) \rightarrow PbO_2^{2-} + 2H_2O\]

Making lead(II) chloride

Lead(II) chloride, a white precipitate, is formed by adding a chloride ions (in dilute hydrochloric acid) to lead(II) nitrate solution. The chemical equation is shown below:

\[Pb^{2+}(aq) + 2Cl^- (aq) \rightarrow PbCl_2 (s)\]

Adding excess concentrated hydrochloric acid dissolves lead(II) chloride by forming soluble, complex ions such as PbCl42-.

Making lead(II) iodide

If you add colorless potassium iodide solution (or any other source of iodide ions in solution) to a solution of lead(II) nitrate, a bright yellow precipitate of lead(II) iodide is produced.

\[ Pb^{2+}(aq) + 2I^- (aq) \rightarrow PbI_2(s)\]

Making lead(II) sulfate

Adding aqueous sulfate ions to a solution of lead(II) nitrate results in a white precipitate of lead(II) sulfate. The most convenient source of sulfate ions is dilute sulfuric acid. The equation is given below:

\[ Pb^{2+} (aq) + SO_4^{2-} (aq) \rightarrow PbSO_4(s)\]

Contributors

Jim Clark (Chemguide.co.uk)